The present invention relates to a seat belt retractor for winding up a seat belt onto a rotational spool.
A passenger car is normally equipped with seat belts for protecting occupants when the car experiences an abrupt deceleration. Such a seat belt device may include a pretensioner which takes up a predetermined amount of seat belt around an occupant in order to restrain the occupant with increased force when an accident such as a vehicle collision is detected.
Currently, there are various types of pretensioners in use. One known type of pretensioner includes a pipe, a gas generator disposed on one end of the pipe, a piston arranged in the pipe, and balls arranged in the pipe. The balls are moved via the piston by gas pressure produced by the gas generator and are discharged through an outlet disposed at the other end of the pipe. A pretensioner gear and a gear connected to a spool are meshed with each other and rotated by the balls being discharged, thereby pretensioning a seat belt.
The present invention provides a seat belt retractor having a structure for preventing the pretensioner from being assembled improperly.
According to the present invention, a seat belt retractor including a spool for winding up a seat belt and a gear fitted to the spool for driving the spool to wind up the seat belt is provided. The gear has two end faces and is configured so that it only fits onto the spool when one of the end faces is adjacent the spool.
According to an alternative embodiment of the present invention, a seat belt retractor for winding up a seat belt is provided. The retractor includes a spool configured to rotate to wind up the seat belt and a gear configured to interfit with the spool so that when the gear rotates the spool rotates about an axis of rotation to wind up the seat belt. The spool includes an external tooth asymmetrical about any plane passing through the axis of rotation of the spool.
The gear may include a surface that contacts the spool, the surface being asymmetrical about a plane perpendicular to the axis of rotation of the spool. The gear may be configured to surround the spool so that the external tooth of the spool engages an internal surface of the gear. The internal surface of the gear may be asymmetrical about a plane perpendicular to the axis of rotation of the spool. The spool may include a plurality of external teeth, and at least one of the teeth may have different dimensions from another one of the teeth.
According to yet another alternative embodiment of the present invention a retractor for winding up a seat belt is provided. The retractor includes a spool and a gear for driving he spool. The gear includes a surface that contacts the spool, the surface being asymmetrical about a plane perpendicular to the axis of rotation of the spool.
According to the present invention, a seat belt retractor for winding up a seat belt by the rotation of a spool may be characterized by including a gear having external teeth not symmetrical about any plane passing through the axis. The gear may be interfitted with the shaft of the spool and fitting portions between the shaft of the spool and the gear may be configured not to be symmetrical about any plane passing through the axis. Therefore, even by taking an action of fitting the gear to the shaft of the spool wrong side out when assembly, the opening of the gear and the periphery of the spool never be fitted to each other so as not to allow the interfit between the gear and the spool. The mistake assembly can be prevented without special attention.
According to the present invention, a seat belt retractor for winding up a seat belt by the rotation of a spool may be characterized by including a gear having external teeth not symmetrical about any plane passing through the axis. The gear may be interfitted with the shaft of the spool, and fitting portions between the shaft of the spool and the gear may be configured not to be symmetrical relative to a plane at the center between one side facing the spool and the other side of the gear. Therefore, even by taking an action of fitting the gear to the shaft of the spool wrong side out when assembly, the opening of the gear and the periphery of the spool never be fitted to each other so as not to allow the interfit between the gear and the spool. The mistake in assembly can be prevented without special attention.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only, and are not restrictive of the invention as claimed.